JP2024543538A - Coated fertilizer granule composition - Google Patents

Abstract

An embodiment of the present disclosure is directed to a coated fertilizer granule composition comprising three polyurethane layers and two wax layers.

Description

Embodiments of the present disclosure are directed to coated fertilizer granule compositions.

Coatings on fertilizers have been used for controlled release of the fertilizer. Controlled release of the fertilizer can increase fertilizer efficiency, lower labor costs associated with fertilization, and/or reduce the amount of fertilizer applied. For some coated fertilizers, exposure to water can cause premature and/or unintended release of the fertilizer. New coated fertilizers and new methods of making coated fertilizers continue to be needed.

The present disclosure provides a coated fertilizer granule composition, the coated fertilizer granule composition comprising: a first polyurethane layer in contact with the fertilizer granule, the first polyurethane layer being made by reacting a high ethylene oxide content polyether polyol with an isocyanate in the presence of a tertiary amine catalyst; a first wax layer in contact with the first polyurethane layer; a second polyurethane layer in contact with the first wax layer, the second polyurethane layer being made by reacting a high propylene oxide content polyether polyol with an isocyanate in the presence of a tertiary amine catalyst; a second wax layer in contact with the second polyurethane layer; and a third polyurethane layer in contact with the second wax layer, the third polyurethane layer being made by reacting castor oil with an isocyanate in the presence of a tertiary amine catalyst.

The above summary of the present disclosure is not intended to describe each disclosed embodiment or every implementation of the present disclosure. More particularly, the present specification illustrates exemplary embodiments. In several places throughout the application, guidance is provided through lists of examples, which examples can be used in various combinations. In each instance, the recited list serves only as a representative group and should not be interpreted as an exclusive list.

Disclosed herein is a coated fertilizer granule composition. The coated fertilizer granule composition may be referred to as including five layers, namely, three polyurethane layers and two wax layers. An embodiment provides that the five layers are concentric with respect to one another. The coated fertilizer granule composition includes a first polyurethane layer in contact with the fertilizer granule, the first polyurethane layer being made by reacting a high ethylene oxide content polyether polyol with an isocyanate in the presence of a tertiary amine catalyst, a first wax layer in contact with the first polyurethane layer, a second polyurethane layer in contact with the first wax layer, the second polyurethane layer being made by reacting a high propylene oxide content polyether with an isocyanate in the presence of a tertiary amine catalyst, a second wax layer in contact with the second polyurethane layer, and a third polyurethane layer in contact with the second wax layer, the third polyurethane layer being made by reacting castor oil with an isocyanate in the presence of a tertiary amine catalyst. Advantageously, the coated fertilizer granule composition disclosed herein can provide improved, i.e., reduced, fertilizer release.

The coated fertilizer granule compositions disclosed herein include fertilizer granules. The fertilizer granules may include a urea source, a nitrogen source, a phosphorus source, or a potassium source, such as, for example, ammonium nitrate, ammonium sulfate, ammonium nitrate sulfate, calcium nitrate, calcium ammonium nitrate, urea-formaldehyde, monoammonium phosphate, diammonium phosphate, polyphosphate compounds, rock phosphate, calcium superphosphate, calcium triphosphate, potassium nitrate, potassium chloride, potassium sulfate, or combinations thereof. In some embodiments, the fertilizer granules include urea. For example, the fertilizer granules may have a nitrogen:phosphorus:potassium ratio of 46:0:0. The amount of nitrogen, phosphorus, or potassium source included in the fertilizer granules may vary based on the intended end use, but may be 0-60% by weight of each component based on the total weight of the fertilizer granule.

Additionally, magnesium sulfate and a source of one or more trace elements, i.e., micronutrients, may be included, e.g., boron, calcium, chlorine, cobalt, copper, iron, manganese, molybdenum, nickel, sodium, zinc, or combinations thereof may be present. These nutrients may be provided in elemental form or in salt form, e.g., sulfates, nitrates, or halides. The amount of micronutrients may vary depending on the intended end use. For example, the amount of micronutrients may be 0.1 to 5 weight percent (wt%) based on the total weight of the fertilizer granule.

In the fertilizer granules, fillers may be utilized, such as bentonite, calcite, calcium oxide, calcium sulfate (anhydrous or hemihydrate), dolomite, talc, sand, or combinations thereof.

Other components of the fertilizer granules may include, for example, regenerated fertilizer particles that may act as surfactants, nucleating agents, or nucleating agent sources, nucleating soil conditioners such as calcium carbonate, activated carbon, elemental sulfur, biocides such as insecticides, herbicides, or fungicides, wicking agents, wetting agents, heat stabilizers, adhesives such as cellulose, polyvinyl alcohol, fats, oils, gum arabic, vinylidene UV stabilizers, antioxidants, reducing agents, colorants, binders such as organic chlorides, zein, gelatin, chitosan, polyethylene oxide polymers, and acrylamide polymers and copolymers, and combinations thereof.

The fertilizer granules may have any shape or size desirable for their intended use. In some embodiments, the fertilizer granules are substantially spherical. The fertilizer granules may have an average particle size of 0.5 to 6.0 millimeters (mm). All individual values and subranges between 0.5 and 6.0 mm are included, for example, the fertilizer granules may have an average particle size of 0.5, 1.0, or 1.5 mm (lower limit) to 6.0, 5.5, or 5.0 mm (upper limit). In some embodiments, at least 90% by weight of the fertilizer granules have a particle size of 2.0 to 4.0 mm. The particle size may be determined according to the "Size Analysis-Sieve Method" IFDC S-107, published by the International Fertilizer Development Center (IFDC), which is a common and internationally accepted method used to determine fertilizer particle size.

The coated fertilizer granule composition includes a first polyurethane layer that contacts, e.g., coats, the fertilizer granule. As used herein, coating refers to covering, e.g., formed on, 90% to 100% of the surface area, e.g., the outermost area, of the fertilizer granule. All individual values and subranges from 90% to 100% are included, e.g., the first polyurethane layer can cover 90, 95, or 96% (lower limits) to 100, 99, or 98% (upper limits) of the surface area of the fertilizer granule.

The embodiment provides that the first polyurethane layer is made by reacting a high ethylene oxide content polyether polyol with a first polyurethane layer isocyanate in the presence of a first polyurethane layer tertiary amine catalyst.

As used herein, "high ethylene oxide content polyether polyol" refers to a polyether polyol produced by polymerization of ethylene oxide and, optionally, another alkylene oxide and an initiator, wherein the ethylene oxide is 80% or more by weight of the total alkylene oxide content of the high ethylene oxide content polyether polyol. Examples of other alkylene oxides that may be utilized include propylene oxide, butylene oxide, and combinations thereof. The embodiment specifies that the ethylene oxide is 80 to 100% by weight of the total alkylene oxide content of the high ethylene oxide content polyether polyol. All individual values and subranges from 80 to 100% by weight are included, for example, the ethylene oxide may be 80, 90, or 95% by weight (lower limit) to 100, 99, 98, or 97% by weight (upper limit) of the total alkylene oxide content of the high ethylene oxide content polyether polyol. One or more embodiments provide that ethylene oxide is 100% by weight of the total alkylene oxide content of the high ethylene oxide content polyether polyol (i.e., no other alkylene oxides are utilized). Examples of initiators include water, glycerin, ethylene glycol, propylene glycol, trimethylolpropane, pentaerythritol, or combinations thereof. The initiator may have a functionality of 2 to 4.

The high ethylene oxide content polyether polyol has a nominal (e.g., average) hydroxyl functionality of 2 to 4. All individual values and subranges from 2 to 4 are included, for example, the high ethylene oxide content polyether polyol can have an average functionality of 2.0, 2.5, or 2.8 (lower limits) to 4.0, 3.5, or 3.2 (upper limits). One or more embodiments provide for a high ethylene oxide content polyether polyol having a nominal hydroxyl functionality of 3.

High ethylene oxide content polyether polyols can be prepared using known equipment, reaction conditions, and reaction components. High ethylene oxide content polyether polyols are commercially available. Examples of commercially available high ethylene oxide content polyether polyols include, but are not limited to, high ethylene oxide content polyether polyols sold under the trade name VORANOL™, such as VORANOL™ IP625, available from The Dow Chemical Company.

The high ethylene oxide content polyether polyol may have an average hydroxyl number of 240 to 300 mg KOH/g. All individual values and subranges between 240 and 300 mg KOH/g are included, for example, the high ethylene oxide content polyether polyol may have an average hydroxyl number of 240, 250, or 265 mg KOH/g (lower limit) to 300, 290, or 285 mg KOH/g (upper limit). The average hydroxyl number as KOH may be determined according to ASTM D4274. One or more embodiments specify that the high ethylene oxide content polyether polyol has an average hydroxyl number of 270 mg KOH/g.

The coated fertilizer granule composition includes a first wax layer that contacts, e.g., coats, the first polyurethane layer. The first wax layer can cover, e.g., be formed on, 90% to 100% of the surface area, e.g., the outermost area, of the first polyurethane layer. All individual values and subranges between 90% and 100% are included, e.g., the first wax layer can cover 90, 95, or 96% (lower limit) to 100, 99, or 98% (upper limit) of the surface area of the first polyurethane layer. The first polyurethane layer separates the first wax layer from the fertilizer granule. In other words, the first polyurethane layer and the first wax layer are separate from each other.

Examples of waxes that may be utilized in the first and second wax layers, as discussed further herein, include insect and animal waxes, such as beeswax, vegetable waxes, such as candelilla, carnauba, Japan wax, Orycury wax, Douglas fir bark wax, rice bran wax, jojoba, castor wax, and white bayberry fruit wax, montan wax, peat wax, ozokerite wax, and ceresin wax, and petroleum waxes, such as paraffin wax, microcrystalline wax, semicrystalline wax, and synthetic waxes, such as polyethylene wax, Fischer-Tropsch wax, copolymer waxes of ethylene, propylene, and/or acrylic acid, and mixtures of petroleum wax and ethylene-vinyl acetate copolymers. In one group of embodiments, petroleum wax and/or synthetic waxes are used. One or more embodiments provide that the wax is an alpha olefin wax. The alpha olefin wax may be a straight chain hydrocarbon having 20 to 30 carbons.

Some embodiments provide that the wax utilized in the first wax layer and the second wax layer is the same wax. Some embodiments provide that the wax utilized in the first wax layer and the second wax layer is a different wax.

The coated fertilizer granule composition includes a second polyurethane layer that contacts, e.g., coats, the first wax layer. The second polyurethane layer can cover, e.g., be formed on, 90% to 100% of the surface area, e.g., outermost area, of the first wax layer. All individual values and subranges between 90% and 100% are included, e.g., the second polyurethane layer can cover 90, 95, or 96% (lower limit) to 100, 99, or 98% (upper limit) of the surface area of the first wax layer. The first wax layer separates the first polyurethane layer from the second polyurethane layer. In other words, the first polyurethane layer, the first wax layer, and the second polyurethane layer are separate from one another.

The embodiment provides that the second polyurethane layer is made by reacting a high propylene oxide content polyether with a second polyurethane layer isocyanate in the presence of a second polyurethane layer tertiary amine catalyst.

As used herein, "high propylene oxide content polyether" refers to a polyether polyol produced by polymerization of propylene oxide and, optionally, another alkylene oxide and an initiator, where the propylene oxide is 80% or more by weight of the total alkylene oxide content of the high propylene oxide content polyether polyol. Examples of other alkylene oxides that may be utilized include ethylene oxide, butylene oxide, and combinations thereof. The embodiment specifies that the propylene oxide is 80 to 100% by weight of the total alkylene oxide content of the high propylene oxide content polyether polyol. All individual values and subranges from 80 to 100% by weight are included, for example, the propylene oxide may be 80, 90, or 95% by weight (lower limits) to 100, 99, 98, or 97% by weight (upper limits) of the total alkylene oxide content of the high propylene oxide content polyether polyol. One or more embodiments provide that propylene oxide is 100% by weight of the total alkylene oxide content of the high propylene oxide content polyether polyol (i.e., no other alkylene oxides are utilized). Examples of initiators include water, glycerin, ethylene glycol, propylene glycol, trimethylolpropane, pentaerythritol, or combinations thereof. The initiator may have a functionality of 2 to 4.

The high propylene oxide content polyether polyol has a nominal (e.g., average) hydroxyl functionality of 2 to 4. All individual values and subranges from 2 to 4 are included, for example, the high propylene oxide content polyether polyol may have an average functionality of 2.0, 2.5, or 2.8 (lower limit) to 4.0, 3.5, or 3.2 (upper limit). One or more embodiments provide for a high propylene oxide content polyether polyol having a nominal hydroxyl functionality of 3. The high propylene oxide content polyether polyol can be prepared using known equipment, reaction conditions, and reaction components. The high propylene oxide content polyether polyol is commercially available. Examples of commercially available high propylene oxide content polyether polyols include, but are not limited to, high propylene oxide content polyether polyols sold under the trade name VORANOL™, such as VORANOL™ 230-238, available from The Dow Chemical Company.

The high propylene oxide content polyether polyol may have an average hydroxyl number of 210 to 650 mg KOH/g. All individual values and subranges between 210 and 650 mg KOH/g are included, for example, the high propylene oxide content polyether polyol may have an average hydroxyl number of 210, 215, or 225 mg KOH/g (lower limit) to 650, 600, 550, 500, 450, 400, 350, 300, 265, 260, or 250 mg KOH/g (upper limit). The average hydroxyl number as KOH may be determined according to ASTM D4274. One or more embodiments specify that the high propylene oxide content polyether polyol has an average hydroxyl number of 240 mg KOH/g.

The coated fertilizer granule composition includes a second wax layer that contacts, e.g., coats, the second polyurethane layer. The second wax layer can cover, e.g., be formed on, 90% to 100% of the surface area, e.g., the outermost area, of the second polyurethane layer. All individual values and subranges between 90% and 100% are included, e.g., the second wax layer can cover 90, 95, or 96% (lower limit) to 100, 99, or 98% (upper limit) of the surface area of the second polyurethane layer. The second polyurethane layer separates the first wax layer from the second wax layer. In other words, the second polyurethane layer, the first wax layer, and the second wax layer are separate from one another.

The coated fertilizer granule composition includes a third polyurethane layer in contact with, e.g., coating, the second wax layer. The third polyurethane layer can cover, e.g., be formed on, 90% to 100% of the surface area, e.g., outermost area, of the second wax layer. All individual values and subranges between 90% and 100% are included, e.g., the third polyurethane layer can cover 90, 95, or 96% (lower limit) to 100, 99, or 98% (upper limit) of the surface area of the second layer. The second wax layer separates the second polyurethane layer from the third polyurethane layer. In other words, the second polyurethane layer, the second wax layer, and the third polyurethane layer are separate from one another.

The third polyurethane layer is made by reacting castor oil with a third polyurethane layer isocyanate in the presence of a third polyurethane layer tertiary amine catalyst. Castor oil is a bio-based polyol with hydroxyl functionality.

Castor oil can be obtained commercially. Examples of commercially available castor oil include, but are not limited to, castor oil sold by Sigma Aldrich.

As described above, the first polyurethane layer isocyanate is utilized to create the first polyurethane layer, the second polyurethane layer isocyanate is utilized to create the second polyurethane layer, and the third polyurethane layer isocyanate is utilized to create the third polyurethane layer. The first polyurethane layer isocyanate, the second polyurethane layer isocyanate, and the third polyurethane layer isocyanate may be the same isocyanate or may be different isocyanates.

Suitable isocyanates include polyisocyanates having an average of more than 1.0 isocyanate groups per molecule. Examples of suitable isocyanates include, among others, polymethylene polyphenylisocyanate, toluene 2,4-/2,6-diisocyanate (TDI), methylene diphenyl diisocyanate (MDI), polymeric MDI, triisocyanatononane (TIN), naphthyl diisocyanate (NDI), 4,4'-diisocyanatodicyclohexylmethane, 3-isocyanatomethyl-3,3,5-trimethylcyclohexyl isocyanate (isophorone diisocyanate IPDI), tetramethylene diisocyanate, hexamethylene diisocyanate (HDI), 2-methylpentamethylene diisocyanate, ... The isocyanate may include, but is not limited to, diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate (THDI), dodecamethylene diisocyanate, 1,4-diisocyanatocyclohexane, 4,4'-diisocyanato-3,3'-dimethyldicyclohexylmethane, 4,4'-diisocyanato-2,2-dicyclohexylpropane, 3-isocyanatomethyl-1-methyl-1-isocyanatocyclohexane (MCI), 1,3-diisooctylcyanato-4-methylcyclohexane, 1,3-diisocyanato-2-methylcyclohexane, and combinations thereof. One or more embodiments provide that the first polyurethane layer isocyanate, the second polyurethane layer isocyanate, and the third polyurethane layer isocyanate are polymethylene polyphenyl isocyanates containing methylene biphenyl diisocyanate.

As noted above, the isocyanate may have an average functionality of greater than 1.0 isocyanate groups per molecule. For example, the isocyanate may have an average functionality of 1.5 to 5.0. All individual values and subranges between 1.5 and 5.0 are included, for example, the isocyanate may have an average functionality of 1.5, 1.7, 2.0, 2.3, or 2.5 (lower limits) to 5.0, 4.5, 4.0, 3.5, or 3.0 (upper limits).

The isocyanate may have an isocyanate equivalent weight of 80 g/eq to 200 g/eq. All individual values and subranges between 80 and 200 g/eq are included, for example, the isocyanate may have an isocyanate equivalent weight of 80, 90, 100, 115, or 120 g/eq (lower limit) to 200, 175, 160, 150, or 145 g/eq (upper limit).

The isocyanate may have an NCO content of 20 to 45 weight percent, based on the total weight of the isocyanate. All individual values and subranges between 20 and 45 weight percent are included, for example, the isocyanate may have an NCO content of 20, 25, or 30 weight percent (lower limit) to 45, 40, or 35 weight percent (upper limit), based on the total weight of the isocyanate.

The isocyanates may be prepared by known processes. The isocyanates may be commercially available. Examples of commercially available isocyanates include, but are not limited to, VORANATE™, VORACOR™, e.g., VORACOR CL100 or VORACOR CE101, and PAPI™, e.g., PAPI™ 27, available from The Dow Chemical Company, among other commercially available isocyanates.

The isocyanate may be utilized to provide an isocyanate index of 120 to 160. All individual values and subranges from 120 to 160 are included, for example, the isocyanate may be utilized to provide an isocyanate index of 120, 130, or 135 (lower limit) to 160, 150, or 145 (upper limit). One or more embodiments provide that the isocyanate may be utilized to provide an isocyanate index of 140. The isocyanate index may be determined as [isocyanate groups/active hydrogen groups x 100]. The active hydrogen groups include those from high ethylene oxide content polyether polyols, high propylene oxide content polyether polyols, castor oil, and tertiary amine catalysts.

The first polyurethane layer tertiary amine catalyst is utilized to make the first polyurethane layer, the second polyurethane layer tertiary amine catalyst is utilized to make the second polyurethane layer, and the third polyurethane layer tertiary amine catalyst is utilized to make the third polyurethane layer. The first polyurethane layer tertiary amine catalyst, the second polyurethane layer tertiary amine catalyst, and the third polyurethane layer tertiary amine catalyst may be the same tertiary amine catalyst or may be different tertiary amine catalysts.

Examples of tertiary amine catalysts include triethanolamine, triisopropanolamine, N-methyl-diethanolamine, N-ethyldiethanolamine, and N,N-dimethyl-ethanolamine. For each of the first, second, and third polyurethane layers, the tertiary amine catalyst may be 5 to 15 weight percent based on the total weight of the tertiary amine catalyst and the respective polyol, i.e., high ethylene oxide content polyether polyol, high propylene oxide content polyether polyol, or castor oil, utilized. All individual values and subranges from 5 to 15 weight percent are included, for example, for each of the first, second, and third polyurethane layers, the tertiary amine catalyst may be 5, 7, or 9 weight percent (lower limit) to 15, 13, or 11 weight percent (upper limit) based on the total weight of the tertiary amine catalyst and the respective polyol utilized. One or more embodiments provide that for each of the first polyurethane layer, the second polyurethane layer, and the third polyurethane layer, the tertiary amine catalyst is 10 wt. %, based on the total weight of the tertiary amine catalyst and the respective polyol utilized.

Embodiments provide that the high ethylene oxide content polyether polyol is 9 to 18 weight percent based on the total weight of the combination of polyurethane-forming components, i.e., high ethylene oxide content polyether polyol, high propylene oxide content polyether polyol, castor oil, isocyanate, and tertiary amine catalyst. All individual values and subranges from 9 to 18 weight percent are included, for example, the high ethylene oxide content polyether polyol can be 9, 11, or 13 weight percent (lower limit) to 18, 16, or 14 weight percent (upper limit) based on the total weight of the combination of polyurethane-forming components.

The embodiment provides that the high propylene oxide content polyether polyol is 9 to 18 weight percent based on the total weight of the combination of polyurethane-forming components, i.e., high ethylene oxide content polyether polyol, high propylene oxide content polyether polyol, castor oil, isocyanate, and tertiary amine catalyst. All individual values and subranges from 9 to 18 weight percent are included, for example, the high propylene oxide content polyether polyol can be 9, 11, or 13 weight percent (lower limit) to 18, 16, or 15 weight percent (upper limit) based on the total weight of the combination of polyurethane-forming components.

Embodiments provide that the castor oil is 11 to 20 weight percent based on the total weight of the combination of polyurethane-forming components, i.e., high ethylene oxide content polyether polyol, high propylene oxide content polyether polyol, castor oil, isocyanate, and tertiary amine catalyst. All individual values and subranges from 11 to 20 weight percent are included, for example, the castor oil can be 11, 13, or 15 weight percent (lower limit) to 20, 18, or 17 weight percent (upper limit) based on the total weight of the combination of polyurethane-forming components.

Embodiments provide that the tertiary amine catalyst is 2 to 8 weight percent based on the total weight of the combination of polyurethane-forming components, i.e., high ethylene oxide content polyether polyol, high propylene oxide content polyether polyol, castor oil, isocyanate, and tertiary amine catalyst. All individual values and subranges from 2 to 8 weight percent are included, for example, the tertiary amine catalyst can be 2, 3, or 4 weight percent (lower limit) to 8, 7, or 6 weight percent (upper limit) based on the total weight of the combination of polyurethane-forming components.

The embodiment specifies that the combination of the first polyurethane layer, the second polyurethane layer, and the third polyurethane layer is 2.0 to 3.5 weight percent based on the total weight of the coated fertilizer granule composition. All individual values and subranges between 2.0 and 3.5 weight percent are included, for example, the combination of the first polyurethane layer, the second polyurethane layer, and the third polyurethane layer can be 2.0, 2.3, or 2.5 weight percent (lower limit) to 3.5, 3.2, or 2.9 weight percent (upper limit) based on the total weight of the coated fertilizer granule composition.

Embodiments provide that the combination of the first and second wax layers is 0.2-0.8% by weight based on the total weight of the coated fertilizer granule composition. All individual values and subranges between 0.2-0.8% by weight are included, for example, the combination of the first and second wax layers can be 0.2, 0.3, or 0.4% by weight (lower limit) to 0.8, 0.7, or 0.6% by weight (upper limit) based on the total weight of the coated fertilizer granule composition.

Embodiments provide that the coated fertilizer granule composition may be made by a variety of processes. The coated fertilizer granule composition may be made utilizing known equipment, conditions, and ingredients.

For example, the coated fertilizer granule composition can be made by utilizing a drum coater. Uncoated fertilizer granules can be added to the drum coater. The ingredients utilized to make the first polyurethane layer (e.g., high ethylene oxide content polyether polyol, first polyurethane layer isocyanate, and first polyurethane layer tertiary amine catalyst) can then be added to the drum coater. These ingredients can be added to the drum coater by various processes. As an example, the high ethylene oxide content polyether polyol and the first polyurethane layer tertiary amine catalyst can be combined to form a mixture, then a portion of the first polyurethane layer isocyanate can be added to the drum coater, then the entire mixture can be added to the drum coater, then the remaining first polyurethane layer isocyanate can be added to the drum coater. The ingredients utilized to make the first wax layer, e.g., first layer wax, can then be added to the drum coater. Then, the ingredients used to make the second polyurethane layer, such as the high propylene oxide content polyether polyol, the second polyurethane layer isocyanate, and the second polyurethane layer tertiary amine catalyst, can be added to the drum coater. These ingredients can be added to the drum coater by various processes. As an example, the high propylene oxide content polyether polyol and the second polyurethane layer tertiary amine catalyst can be combined to form a mixture, and then a portion of the second polyurethane layer isocyanate can be added to the drum coater, followed by adding the entire mixture to the drum coater, followed by adding the remaining second polyurethane layer isocyanate to the drum coater. Then, the ingredients used to make the second wax layer, such as the second layer wax, can be added to the drum coater. The ingredients utilized to make the third polyurethane layer, such as castor oil, the third polyurethane layer isocyanate, and the third polyurethane layer tertiary amine catalyst, can then be added to the drum coater to provide a coated fertilizer granule composition comprising five concentric layers, i.e., three polyurethane layers and two wax layers (polyurethane layer/wax layer/polyurethane layer/wax layer/polyurethane layer). These ingredients can be added to the drum coater by a variety of processes. As an example, the castor oil and the third polyurethane layer tertiary amine catalyst can be combined to form a mixture, and then a portion of the third polyurethane layer isocyanate can be added to the drum coater, followed by adding the entire mixture to the drum coater, followed by adding the remaining third polyurethane layer isocyanate to the drum coater.

The examples use various terms and names for materials, including, for example:

A high ethylene oxide content polyether polyol, Polyol A, was utilized. The high ethylene oxide content polyether polyol was a glycerin initiated all ethylene oxide (100% EO by weight of total alkylene oxide content) fed polyol with a hydroxyl functionality of about 3 and an average hydroxyl number of 270 mg KOH/g.

A high propylene oxide content polyether polyol, Polyol B, was utilized. The high propylene oxide content polyether polyol was a glycerin initiated, all propylene oxide (100% by weight PO of total alkylene oxide content) fed polyol with a hydroxyl functionality of about 3 and an average hydroxyl number of 241 mg KOH/g.

Castor oil (obtained from Sigma Aldrich).

Tertiary amine catalyst (triethanolamine; available from The Dow Chemical Company).

Wax (alpha olefin wax; ALPHAPLUS C30+HA; available from Chevron Phillips Chemical Company LP).

PAPI™ 27 (isocyanate; polymethylene polyphenylisocyanate containing methylene biphenyl diisocyanate (MDI); average functionality 2.7, containing 32.0 wt% NCO, available from The Dow Chemical Company).

Fertilizer (SUPERU 46-0-0, 2-4 mm uncoated urea prills, available from American Plant Food Co.).

Example 1: A coated fertilizer granule composition was prepared as follows: Fertilizer (1000 grams) was oven dried at 80°C for 6 hours. A drum coater (stainless steel drum with 9 3/8 inch open face, 16 1/8 inch diameter, 5 1/8 inch track depth, 1/2 inch evenly spaced vanes (5 total)) was preheated to 70°C and the dry fertilizer was added to the drum coater. The drum coater was run (40 rpm) and the drum coater contents were maintained at 80°C.

Polyol Mixture #1 (4.1 grams) was formed by combining Polyol A and Tertiary Amine Catalyst (Polyol Mixture #1 contained 10% by weight of Tertiary Amine Catalyst) in a container and mixing at 2000 rpm for approximately 1 minute. Polyol Mixture #1 was added to each syringe. Isocyanate #1 (4.9 grams of PAPI™ 27) was added to each syringe.

Polyol Mixture #2 (4.3 grams) was formed by combining Polyol B and Tertiary Amine Catalyst (Polyol Mixture #2 contained 10% by weight of Tertiary Amine Catalyst) in a container and mixing at 2000 rpm for approximately 1 minute. Polyol Mixture #2 was added to each syringe. Isocyanate #2 (4.7 grams of PAPI™ 27) was added to each syringe.

Polyol Mixture #3 (4.8 grams) was formed by combining castor oil and tertiary amine catalyst (Polyol Mixture #3 contained 10% by weight tertiary amine catalyst) in a container and mixing at 2000 rpm for approximately 1 minute. Polyol Mixture #3 was added to each syringe. Isocyanate #3 (4.2 grams of PAPI™ 27) was added to each syringe.

With the drum coater filled with dry fertilizer at 80°C and 40 rpm, 40% by volume of the Isocyanate #1 syringe was added to the contents of the drum coater. After 30 seconds, 100% by volume of the Polyol Mixture #1 syringe was added to the contents of the drum coater. After 30 seconds, the remaining 60% by volume of the Isocyanate #1 syringe was added to the contents of the drum coater (thus adding the components of the first polyurethane layer to the drum coater).

After 30 seconds, wax (2.5 grams; solids) was added to the contents of the drum coater (thus adding the first wax layer ingredients to the drum coater).

After 30 seconds, 40% by volume of the Isocyanate #2 syringe was added to the contents of the drum coater. After 30 seconds, 100% by volume of the Polyol Mixture #2 syringe was added to the contents of the drum coater. After 30 seconds, the remaining 60% by volume of the Isocyanate #2 syringe was added to the contents of the drum coater (thus adding the components of the second polyurethane layer to the drum coater).

After 30 seconds, wax (2.5 grams; solids) was added to the contents of the drum coater (thus adding the first wax layer ingredients to the drum coater).

After 30 seconds, 40% by volume of the Isocyanate #3 syringe was added to the contents of the drum coater. After 30 seconds, 100% by volume of the Polyol Mixture #3 syringe was added to the contents of the drum coater. After 30 seconds, the remaining 60% by volume of the Isocyanate #3 syringe was added to the contents of the drum coater (thus adding the components of the third polyurethane layer to the drum coater).

After 30 seconds, the drum coater was turned off while maintaining 40 rpm until the contents of the drum coater reached approximately 55°C. The drum coater was then stopped rotating and the coated fertilizer granules were removed with a scoop and placed on a tray.

The ingredients and amounts utilized to make Example 1 (Ex1) are reported in Table 1. Comparative Examples A through F (CE A through F) were made similarly to Example 1 with any variations reported in Table 1.

Approximately seven days after preparation, 10 grams of each of Example 1 and Comparative Examples A-F were placed into respective containers along with 100 mL of deionized water. Refractive index measurements were then taken 14 and 28 days after placement into each container to determine the weight percent of fertilizer (urea) released. To determine the refractive index, an initial calibration curve was made by measuring the refractive index of various concentrations of aqueous uncoated urea (SUPERU 46-0-0; 2-4 mm uncoated urea prills) solutions using a refractometer. To determine the weight percent of dissolved urea, the equation was solved as follows:

where X is the weight percent of urea released. A calibration curve plotting the weight percent urea in deionized water versus refractive index had a best fit line: y=0.0013x+1.333, and R ² =0.9997.

The results are reported in Table 2.

The data in Table 2 show that Example 1 advantageously provided improved, i.e., reduced, fertilizer release at both 14 and 28 days compared to each of Comparative Examples A-F.

The tack-free cure time for Polyol Mixture #1 and Polyol Mixture #3 with PAPI™ 27 (Isocyanate Index 140) was determined as the time interval at which a sample of the composition became tack-free to the touch. The results are reported in Table 3.

The data in Table 3 show that Polyol Mixture #1 had a shorter tack-free cure time compared to Polyol Mixture #3. A shorter tack-free cure time indicates a higher reactivity. Polyol Mixture #1, which has a shorter tack-free cure time, can be utilized before Polyol Mixture #3 in producing the coated fertilizer granule composition, thereby advantageously increasing productivity.

Claims (10)

A coated fertilizer granule composition comprising:
a first polyurethane layer in contact with the fertilizer granules, the first polyurethane layer being made by reacting a high ethylene oxide content polyether polyol with an isocyanate in the presence of a tertiary amine catalyst;
a first wax layer in contact with the first polyurethane layer;
a second polyurethane layer in contact with the first wax layer, the second polyurethane layer being prepared by reacting a high propylene oxide content polyether polyol with an isocyanate in the presence of a tertiary amine catalyst;
a second wax layer in contact with the second polyurethane layer;
a third polyurethane layer in contact with the second wax layer, the third polyurethane layer being prepared by reacting castor oil with an isocyanate in the presence of a tertiary amine catalyst;
1. A coated fertilizer granule composition comprising: The coated fertilizer granule composition of claim 1, wherein the first polyurethane layer isocyanate, the second polyurethane layer isocyanate, and the third polyurethane layer isocyanate are polymethylene polyphenyl isocyanate containing methylene biphenyl diisocyanate, and the first polyurethane layer tertiary amine catalyst, the second polyurethane layer tertiary amine catalyst, and the third polyurethane layer tertiary amine catalyst are triethanolamine. The coated fertilizer granule composition of claim 2, wherein ethylene oxide is 80-100 weight percent of the total alkylene oxide content of the high ethylene oxide content polyether polyol, the high ethylene oxide content polyether polyol having a nominal hydroxyl functionality of 2-4, an average hydroxyl number of 240-300 mg KOH/g, and is 9-18 weight percent based on the total weight of the combination of the high ethylene oxide content polyether polyol, the high propylene oxide content polyether polyol, the castor oil, and the polymethylene polyphenylisocyanate containing methylene biphenyl diisocyanate. The coated fertilizer granule composition of claim 3, wherein propylene oxide is 80 to 100 weight percent of the total alkylene oxide content of the high propylene oxide content polyether polyol, the high propylene oxide content polyether polyol having a nominal hydroxyl functionality of 2 to 4, an average hydroxyl number of 210 to 650 mg KOH/g, and is 9 to 18 weight percent based on the total weight of the combination of the high ethylene oxide content polyether polyol, the high propylene oxide content polyether polyol, the castor oil, and the polymethylene polyphenylisocyanate containing methylene biphenyl diisocyanate. The coated fertilizer granule composition of claim 4, wherein the castor oil is 11 to 20 weight percent based on the total weight of the combination of the high ethylene oxide content polyether polyol, the high propylene oxide content polyether polyol, the castor oil, and the polymethylene polyphenylisocyanate containing methylene biphenyl diisocyanate. The coated fertilizer granule composition of claim 5, wherein the combination of the first polyurethane layer, the second polyurethane layer, and the third polyurethane layer is 2.0 to 3.5 weight percent based on the total weight of the coated fertilizer granule composition. The coated fertilizer granule composition of claim 6, wherein the combination of the first wax layer and the second wax layer is 0.2 to 0.8 weight percent based on the total weight of the coated fertilizer granule composition. The coated fertilizer granule composition of claim 1, wherein the first polyurethane layer separates the first wax layer from the fertilizer granule, the first wax layer separates the first polyurethane layer from the second polyurethane layer, the second polyurethane layer separates the first wax layer from the second wax layer, and the second wax layer separates the second polyurethane layer from the third polyurethane layer. The coated fertilizer granule composition of claim 1, wherein the fertilizer granule comprises urea. 10. A method for producing the coated fertilizer granule composition of claim 1, comprising the steps of:
forming the first polyurethane layer followed by forming the first wax layer;
forming the first wax layer followed by forming the second polyurethane layer;
forming the second polyurethane layer followed by forming the second wax layer;
forming the second wax layer followed by forming the third polyurethane layer;
The method includes: